NIAB Root Assessments Confirm Early Take-All Build-Up

April 2004 - Warm, wet spring conditions appear to be encouraging the early build-up of take-all in wheat crops this season, according to initial assessments by NIAB at its Cambridge second wheat trials site. Indeed, a NIAB take-all index of 19 recorded in root samples taken at GS31 suggests untreated second wheat crops, in particular, may be facing the potential for fairly serious 2004 yield losses from the disease.

"The very dry September undoubtedly restricted early take-all infections last autumn," commented NIAB pathologist, Bruce Napier. "Even so, the current infection level compares with a root index of 10 recorded in early 1999/2000 assessments at one of our notably high take-all loss sites. This indicates the disease may well have gained a decent foot-hold in many untreated crops despite their decidedly late drilling and emergence.

"In marked contrast to last season, when the early drought proved valuable in arresting take-all development, conditions this spring have definitely played into the hands of the disease."

If the wet conditions persist, Bruce Napier warns that infection levels could easily build quite markedly over the coming few critical weeks to create real problems for some growers; especially if a dry summer poses a particular challenge to crop performance. "It's too early to be certain, but at the moment I think we are looking at a take-all year similar to 2003," he said. "Although it could quite easily escalate to cause the generally higher losses we experienced in 2002.

"I would advise growers to check for take-all carefully this summer with root assessments. First wheats after set aside or barley are at risk of the disease as well as second wheats, so careful observation of all crops will be invaluable in identifying areas at particular risk and likely to profit from more active take-all management if put into wheat in 2004/5."